1. Field of the Invention
The present invention relates to a tape cassette, and more particularly, to a shape of its positioning part suitable for the improvement of positioning accuracy in loading the tape cassette to a magnetic recording/reproducing apparatus.
2. Related Art
The tape cassette with built-in reels for winding a magnetic tape, when loaded to an apparatus which performs recording and reproduction, is positioned in a way that the reels and the tape cassette casing are positioned independently of each other. That is, the reels are positioned by a reel base of the apparatus, and the tape cassette casing is positioned by a positioning member of the apparatus.
In conventional tape cassettes, the plane or hole by which a tape cassette casing is positioned is generally provided to the outermost side face, i.e. the lowest face of the casing, for example as in the D1 or D2 tape cassette described in "SMPTE Journal," March 1986, pp. 358-374. Such a configuration is simplest in construction. Also, such a configuration allows the reference plane or hole to be provided without being much affected by the internal construction, thus suitable for offering thinner tape cassettes.
However, in the above described prior art, accuracy of the reference plane of the tape cassette, especially retention of the accuracy has not been taken into consideration. More specifically, the tape cassette is normally loaded on the apparatus by a cassette loading mechanism. When this is done, the casing surface of the tape cassette is put into sliding contact with the cassette loading mechanism. Repeating such action makes the cassette surface vulnerable to damage. Further, the casing surface is likely to make contact with any foreign matter in transport of the tape cassette or other handling, which could easily lead to a deterioration in surface accuracy. If surface accuracy of the reference plane of the tape cassette deteriorates, the tape cassette, when loaded on an apparatus, will result in the incorrect positioning of the tape cassette relative to the apparatus, in which case the tape cassette can no longer be loaded horizontally. As a result, the reels may come into rubbing contact with the casing at the inside of the tape cassette, or the accuracy of the tape guide inside the tape cassette may be negatively affected, resulting in an unstable tape running.
Meanwhile, in recent years, VTRs have been widely used as mini-movies, and increasingly used outdoors. Under such use environments, there is a demand for heavy duty type tape cassettes that will not be damaged even if dropped, besides the need for dust-proof and drip-proof features. Considering such demands from the market, the aforementioned prior art has not been able to provide sufficient adjustments.